[ACII PC] Saving glitch?

Yesterday I started AC II and got to the Villa in Monteriggioni. Now today I wanted to play again but to my surprise when I went to my profile I was at Abstergo. I played a bit (had to start over), then stopped. Now I start playing again and my profile says I'm back at Monteriggioni. Why is this? Can I stop it from happening in the future?